Temporary closure of Heathrow Terminal 4 stations: Due to a significant drop in demand, all flights to/from Heathrow Airport are operating from Terminals 2 & 5 only. The Piccadilly line and TfL Rail stations at Terminal 4 are closed until further notice. All Piccadilly line and TfL Rail services to the airport are operating to/from Heathrow T1,2,3 & 5 stations. To check flight departure and arrivals.

Temporary closure of Heathrow Terminal 4 stations: Due to a significant drop in demand, all flights to/from Heathrow Airport are operating from Terminals 2 & 5 only. The Piccadilly line and TfL Rail stations at Terminal 4 are closed until further notice. All Piccadilly line and TfL Rail services to the airport are operating to/from Heathrow T1,2,3 & 5 stations. To check flight departure and arrivals.

This is indeed what it says on the station status page. TfL don't know the name of their own station.

Royal Oak to Bethnal Green in 333 days
Heathrow Terminal 4 to Amersham in 17 hours, 42 minutes and 22 seconds